The following table provides information about the amount of gross gains and losses realized through the sales of available-for-sale investment securities:


	Three Months Ended March 31
(Dollars in Millions)	2023			2022
Realized gains	$	60		$	242
Realized losses		(92	)		(224	)
Net realized gains (losses)	$	(32	)	$	18
Income tax on net realized gains (losses)	$	(8	)	$	4

The Company conducts a regular assessment of its available-for-sale investment securities with unrealized losses to determine whether all or some portion of a security’s unrealized loss is related to credit and an allowance for credit losses is necessary. If the Company intends to sell or it is more likely than not the Company will be required to sell an investment security, the amortized cost of the security is written down to fair value. When evaluating credit losses, the Company considers various factors such as the nature of the investment security, the credit ratings or financial condition of the issuer, the extent of the unrealized loss, expected cash flows of underlying collateral, the existence of any government or agency guarantees, and market conditions. The Company measures the allowance for credit losses using market information where available and discounting the cash flows at the original effective rate of the investment security. The allowance for credit losses is adjusted each period through earnings and can be subsequently recovered. The allowance for credit losses on the Company’s available-for-sale investment securities was immaterial at March 31, 2023 and December 31, 2022.

At March 31, 2023, certain investment securities had a fair value below amortized cost. The following table shows the gross unrealized losses and fair value of the Company’s available-for-sale investment securities with unrealized losses, aggregated by investment category and length of time the individual investment securities have been in continuous unrealized loss positions, at March 31, 2023:


	Less Than 12 Months					12 Months or Greater					Total
(Dollars in Millions)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. Treasury and agencies	$	359	$	(11	)	$	17,134	$	(2,359	)	$	17,493	$	(2,370	)
Mortgage-backed securities
Residential agency		6,121		(252	)		19,435		(2,077	)		25,556		(2,329	)
Commercial
Agency		—		—			7,300		(1,427	)		7,300		(1,427	)
Non-agency		7		—			—		—			7		—
Asset-backed securities		3,140		(33	)		—		—			3,140		(33	)
Obligations of state and political subdivisions		4,550		(126	)		4,198		(950	)		8,748		(1,076	)
Other		—		—			4		—			4		—
Total investment securities	$	14,177	$	(422	)	$	48,071	$	(6,813	)	$	62,248	$	(7,235	)

These unrealized losses primarily relate to changes in interest rates and market spreads subsequent to purchase of these available-for-sale investment securities. U.S. Treasury and agencies securities and agency mortgage-backed securities are issued, guaranteed or otherwise supported by the United States government. The Company’s obligations of state and political subdivisions are generally high grade. Accordingly, the Company does not consider these unrealized losses to be credit-related and an allowance for credit losses is not necessary. In general, the issuers of the investment securities are contractually prohibited from prepayment at less than par, and the Company did not pay significant purchase premiums for these investment securities. At March 31, 2023, the Company had no plans to sell investment securities with unrealized losses, and believes it is more likely than not it would not be required to sell such investment securities before recovery of their amortized cost.

During the three months ended March 31, 2023 and 2022, the Company did not purchase any investment securities that had more-than-insignificant credit deterioration.

All of the Company’s held-to-maturity investment securities are U.S. Treasury and agencies securities and highly rated agency mortgage-backed securities that are guaranteed or otherwise supported by the United States government and have no history of credit losses. Accordingly the Company does not expect to incur any credit losses on held-to-maturity investment securities and has no allowance for credit losses recorded for these securities.

The following table provides information about the amortized cost, fair value and yield by maturity date of the investment securities outstanding at March 31, 2023:


(Dollars in Millions)	Amortized Cost		Fair Value		Weighted- Average Maturity in Years		Weighted- Average Yield (e)
Held-to-maturity
U.S. Treasury and Agencies
Maturing in one year or less	$	—	$	—		—		—	%
Maturing after one year through five years		1,344		1,307		3.0		2.85
Maturing after five years through ten years		—		—		—		—
Maturing after ten years		—		—		—		—
Total	$	1,344	$	1,307		3.0		2.85	%
Mortgage-Backed Securities (a)
Maturing in one year or less	$	22	$	21		.8		5.09	%
Maturing after one year through five years		1,531		1,536		2.7		4.58
Maturing after five years through ten years		79,376		70,881		9.0		2.20
Maturing after ten years		6,189		5,131		10.2		1.93
Total	$	87,118	$	77,569		9.0		2.23	%
Total held-to-maturity (b)	$	88,462	$	78,876		8.9		2.24	%
Available-for-sale
U.S. Treasury and Agencies
Maturing in one year or less	$	261	$	261		.2		4.75	%
Maturing after one year through five years		4,452		4,114		3.9		1.70
Maturing after five years through ten years		13,339		11,829		7.0		1.93
Maturing after ten years		2,369		1,850		11.2		2.00
Total	$	20,421	$	18,054		6.7		1.92	%
Mortgage-Backed Securities (a)
Maturing in one year or less	$	71	$	70		.8		2.44	%
Maturing after one year through five years		9,603		9,020		3.1		2.44
Maturing after five years through ten years		26,252		23,248		7.5		2.94
Maturing after ten years		1,275		1,114		11.1		3.55
Total	$	37,201	$	33,452		6.5		2.83	%
Asset-Backed Securities
Maturing in one year or less	$	3,054	$	3,021		.4		4.25	%
Maturing after one year through five years		506		509		3.2		6.94
Maturing after five years through ten years		276		277		5.7		5.77
Maturing after ten years		—		—		—		—
Total	$	3,836	$	3,807		1.2		4.72	%
Obligations of State and Political
Subdivisions (c) (d)
Maturing in one year or less	$	152	$	153		.3		5.12	%
Maturing after one year through five years		3,579		3,550		3.7		4.51
Maturing after five years through ten years		1,556		1,488		7.8		3.89
Maturing after ten years		5,947		4,983		16.2		3.21
Total	$	11,234	$	10,174		10.8		3.74	%
Other
Maturing in one year or less	$	—	$	—		—		—	%
Maturing after one year through five years		4		4		2.2		1.89
Maturing after five years through ten years		—		—		—		—
Maturing after ten years		—		—		—		—
Total	$	4	$	4		2.2		1.89	%
Total available-for-sale (b)	$	72,696	$	65,491		7.0		2.82	%

(a)	Information related to asset and mortgage-backed securities included above is presented based upon weighted-average maturities that take into account anticipated future prepayments.

(b)

The weighted-average maturity of total held-to-maturity investment securities was 9.2 years at December 31, 2022, with a corresponding weighted-average yield of 2.18 percent. The weighted-average maturity of total available-for-sale investment securities was 7.4 years at December 31, 2022, with a corresponding weighted-average yield of 2.94 percent.

(c)	Information related to obligations of state and political subdivisions is presented based upon yield to first optional call date if the security is purchased at a premium, and yield to maturity if the security is purchased at par or a discount.

(d)	Maturity calculations for obligations of state and political subdivisions are based on the first optional call date for securities with a fair value above par and the contractual maturity date for securities with a fair value equal to or below par.

(e)

Weighted-average yields for obligations of state and political subdivisions are presented on a fully-taxable equivalent basis based on a federal income tax rate of 21 percent. Yields on investment securities are computed based on amortized cost balances, excluding any premiums or discounts recorded related to the transfer of investment securities at fair value from available-for-sale to held-to-maturity.